Add authorized IPs to control nodes.

[lukevers]

Because most nodes are headless servers, some people are having difficulty editing/adding their nodes. Although we support curl and wget POSTS, sometimes it is not enough. I'm just going to paste some lines from IRC that we discussed.

<lukevers> say you want to "authorize this node from this ip"
<lukevers> it'd send an email to the node
<lukevers> telling what is going on and saying that only click this verify link if you accept
<lukevers> and only give a short period of time for the verify link to be active
<lukevers> in the database it could be stored under authorizedips or something
<lukevers> also, we should still assume the ip trying to do this matches the netmask if available
<lukevers> DuoNoxSol: thoughts? 
<DuoNoxSol> that's actually a good idea
<lukevers> while we still also allow curl/wget
<lukevers> and recommend highly to use that instead
<lukevers> but if you must, you can do this
<DuoNoxSol> you'd still end up having to use it once in order to do the verify
<lukevers> oh yeah